1. Field of the Invention
This invention relates generally to an assembly having an electrical machine and a power electronics unit for use in a vehicle.
2. Description of the Prior Art
Assemblies of this type are used in electrically powered vehicles, such as industrial trucks, for example. The power electronics unit is frequently a converter. The electrical machine can be, for example, the propulsion motor of the vehicle. In that case, the propulsion motor is supplied with electrical energy by means of the power electronics unit. In an additional application, for example on a vehicle that uses diesel-electric propulsion, the electrical machine can be a generator, whereby the electrical energy generated by the generator is supplied to the power electronics unit.
On similar assemblies of the prior art, the electrical machine and the power electronics unit are located separately from one another. Frequently, the housing for the electrical machine and the housing for the power electronics unit are fastened separately from each other to the frame of the vehicle. An electrical connection between the electrical machine and the power electronics unit is generally created using cables and screwed electrical connections. The type of cable and screwed connections used are determined by the intensity of the current to be transmitted as well as by the stresses that are likely to be encountered. Because the screwed electrical connections must be protected from external influences such as dirt or moisture, the screwed connections on similar assemblies of the prior art are typically provided with an additional cover.
The manufacture and service of prior art assemblies are time-consuming and material-intensive processes. Therefore, it is an object of this invention to provide an assembly that is easy to manufacture having an electrical machine and a power electronics unit which can be used in a vehicle.
The invention teaches that a housing part of the electrical machine is connected with a housing part of the power electronics unit at a seam between the two parts, and electrical pressure contacts are located in the vicinity of the seam between the two parts. The seam between the two parts is preferably substantially flat. The power electronics unit preferably is fastened directly to the electrical machine, for example by means of threaded fasteners, as a result of which the seam between the two parts can be substantially flat.
The pressure contacts located in the vicinity of the seam between the two parts are automatically connected to the electrical machine during the installation of the power electronics unit. In this case, each pressure contact has one contact face or point located on the power electronics unit and one contact face or point on the electrical machine. To promote secure electrical contact and to compensate for potential manufacturing tolerances, at least one contact point of a pressure contact is spring-loaded toward the other contact point of the same pressure contact.
It is appropriate that at least one seal is located in the vicinity of the seam between the two parts. The seal is located between the housing parts of the power electronics unit and the electrical machine, and protects the pressure contacts against external influences such as dust and moisture. If there are means to center the contact points in the vicinity of the seam between the two parts, this ensures that the power electronics unit and the electrical machine can be operationally connected to one another only in the correct position. Thus, the creation of unintentional electrical connections or short circuits is practically impossible. At least some of the electrical pressure contacts are provided to electrically connect the power electronics unit with the electrical machine. Thus, no cable connections located outside the housing are necessary between the electrical machine and the power electronics unit.
In one advantageous embodiment of the invention, at least some of the electrical pressure contacts are provided for the electrical connection of the power electronics unit and additional electrical assemblies or units of the vehicle, whereby lines to these assemblies or units may be laid through the housing part of the electrical machine. The additional electrical assemblies in question can include, for example, a braking resistance or a power supply unit. In this manner, all of the electrical connections of the power electronics unit can be in the form of pressure contacts, in which case it becomes possible to eliminate exposed lines.
In summary, the following advantages are achieved by electrical connections in the form of pressure contacts according to the invention:
Errors caused by incorrect assembly, such as mixups in the connections or insufficient tightening of the screwed connections used previously, become impossible.
Assembly and installation time is significantly reduced, because the connection of the contacts is completed with the installation of the power electronics unit.
Electrical components can be replaced quickly and correctly, even under difficult conditions, such as during service at the site where the vehicle is being operated.
Apart from the seal of the seam between the two parts, no special measures are required to provide protection against outside influences.